California’s Ancient Vernal Pools Remain a Vital Ecological Resource

Vernal pools are important natural resources, especially in California. Vernal pools are flooded depressions in areas of ancient volcanic mudflows, hardpan, and claypan, all of which retain water longer than their surrounding uplands (though they generally dry up as warm weather approaches). It’s not unusual for vernal pools to go through several fill-and-dry up cycles during a rainy season, which means only plants and animals that are specifically adapted to such cycles can survive in them.

As spring rains fill the pools, various freshwater invertebrates, crustaceans, and amphibians begin to emerge. A number of indigenous plants begin to sprout, as well, some of which have evolved unique floating leaves and air-filled stems in order to stay afloat. The pools also attract a great many birds who rely on the abundant plant and animal life found there for food and shelter.

Over the centuries, vernal pools have played a significant part in human history, as well. A great many ancient stone food preparation tools have been unearthed surrounding many modern day vernal pools, suggesting that Native Americans used those pools as a food source for vegetables such as coyote thistles (related to modern carrots). As the season progressed, Native Americans also ground various seeds from around the pools into a seed stew they called pinole, grinding the seeds with stone mortars and pestles.

Birds were hunted at the pools through the use of nets that were fastened to poles and stretched across the water. Ancient hunters chased birds into the nets where they became entangled.

Many native species of plants that have thrived in and around vernal pools for millennia have begun to provide modern humans with potentially important resources, as well. For example, meadowfoam has recently shown promise as a source of oil that could replace animal-based oils in a number of industrial applications.

California’s Central Valley, home to many vernal pools, is a part of an annual migratory bird route known as the Pacific Flyway, which extends from Alaska to South America. Every spring sees thousands of migrating birds resting and feeding in the Central Valley’s network of vernal pools, and protein provided by the crustaceans and invertebrates that inhabit the pools represents an important food source for migrating and native bird populations.

Another important function of vernal pools is their ability to moderate seasonal flooding in the spring, which helps prevent a great deal of agricultural and urban contaminants from entering California’s water system. The overall importance of this fact alone is difficult to calculate, but there’s no doubt that vernal pools play a major role in helping to keep California’s water clean.

There are a number of state, local, and federal laws that regulate activities in and around vernal pools, all of which are designed to minimize any danger to the various threatened or endangered wildlife and plant species who make those pools their home. The California Environmental Quality Act also requires public agencies to consider the effect on those biological resources before any proposed actions are carried out.

There are a number of other environmental laws and policies affecting anyone seeking to engage in activities in and around vernal pools that have been passed by the state of California, but by the federal government to further protect that vital resource. Some of the policies that have been instituted include: the Federal Clean Water Act, the Migratory Bird Treaty Act, the California Endangered Species Act and California Fish and Game Code, the Endangered Species Act, and the California Environmental Quality Act.

All of those environmental laws and policies were passed in order to make it mandatory for both agencies and private landowners to become keenly aware of the potentially harmful effects of their proposed actions on vernal pools or other environmental situations. The overall intent is to have anyone proposing to engage in activities in or around vernal pools study the potential impact (well before any action is taken) to make certain that no less damaging alternative exists. Mandating permits and compliance with strict guidelines forces agencies and individuals to carefully consider their actions before moving forward.

With careful management and constant vigilance to make sure they’re left as undisturbed and natural as possible, California’s ancient vernal pools will continue to provide a vital ecosystem for a wide variety of plants and animals, as well as protecting California’s citizens from further pollution of water, which is one of the state’s most precious resources. The important thing is to educate the public as to the importance of those pools and to make certain that the various policies and laws that have been passed to protect them aren’t diluted over time. Like everything in the natural world, California’s vernal pools can only survive if their overall importance is acknowledged and protected.